1. Field of the Invention
The present invention relates to an ultrasound observation apparatus, an ultrasound observation system, and an actuation method for the ultrasound observation apparatus for generating an image including an elastic image based on an ultrasound signal obtained by transmitting and receiving ultrasound.
2. Description of the Related Art
An ultrasound observation apparatus that generates, from a distortion amount of a biological tissue caused by an oppression force, an elastic image representing hardness or softness of the biological tissue has been put to practical use.
A series of images acquired in such an ultrasound observation apparatus are once stored in an image memory or the like. A user selects, out of the series of images stored in the image memory, a proper image as an image for calculating elasticity information and an image for medical record storage.
Incidentally, when the ultrasound observation apparatus is set in an elastic image observation mode, a region having a distortion amount is larger than a predetermined threshold in an image is sometimes colored and displayed. However, not all frame images are always colored. Therefore, when the user selects the proper image, the user has to search for the proper image not only in colored frame images but also uncolored frame images.
In order to cope with such a point, for example, International Publication No. 2011/010626 discloses a technique for automatically extracting a proper image based on an oppression state to an organism. References used for extraction in the publication are an average of displacement, an average of elasticity information, displacement of pressure, fluctuation in pressure in a beam line direction, and the like.
Japanese Patent Application Laid-Open Publication No. 2012-213545 discloses an ultrasound diagnostic apparatus that, in order to provide a high-quality three-dimensional elastic image, determines elastic volume data formed by a plurality of two-dimensional elastic image including a noise image as a noise volume and hides a three-dimensional elastic image by the elastic volume data determined as the noise volume.
Further, Japanese Patent Application Laid-Open Publication No. 2005-118152 describes a technique for, in order to provide a high-quality elastic image, evaluating, based on various data (pressure data, displacement frame data, and elastic frame data) used in a generation process of a distortion elastic image (elastic frame data), a value of performing image display concerning respective measurement points in a region of interest (ROI), distinguishing useless information and useful information, and finally not leaving (masking to hide) the useless information as an image.